Telephone



(No Model.)

H. S. PAGE. TELEPHONE.

,720. Patented Jan. 30, 1894.

Fig. 5.

UNITED STATES PATENT OFFICE,

HERBERT S. PAGE, OF SOMERVILLE, MASSACHUSETTS, ASSIGNOR OF FIVE- SIXTHSTO JOHN K. WHITING, OF SAME PLACE, AND HARVEY A. HOP- KINS, OFWELLINGTON, MASSACHUSETTS.

TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 513,720, dated January30, 1894.

Application filed May 15, 1893.

.To on whom it may concern.-

Be it known that I, HERBERT S. PAGE, of Sommerville, in the county ofMiddlesex and State of Massachusetts, have invented certain new anduseful Improvements in Microphonic Telephone-Transmitters, of which thefollowing is a specification. My invention relates to microphonictelephone transmitters of that class which employ a diaphragm to receivethe air vibrations produced by the voice and transmit the same to theelectrodes, which are included in the primary of an inductive coil witha battery, or which are placed directly in the line cirr 5 cuit. In suchtransmitters, of which the well known Blake instrument is the type,unless the electrodes are very finely adjusted, they brea or separateunder the violent vibrations produced in loud speaking, and consezoquently fail to transmit the words spoken; and owing to there beingpractically but two points of contact between the electrodes, it

is impossible to employ but a small amount of battery, and consequentlythe voice can- 2 5 not be transmitted to as great a distance,

as it is desirable under all circumstances, and

when breaks occur between the electrodes sparks are produced which makeslight holes in or roughening of the carbon surface and cause imperfectcontact. It is well known that instruments of this type produce veryclear and beautiful articulation in the receiving telephone, and it isdesirable in View of this fact to employ this form in long dis- 3 5tance talking if possible, and to this end my invention tends.

My invention consists therefore in providing means associated with amicrophonic telephone transmitter of the Blake type whereby it may beused in long distance talking in which the disagreeable annoyancescaused by breaks at the electrodes are obviated.

The said means consist essentially of a diaphragm of glass, porcelain orother similar 5 non-conducting material the outer face of which iscarbonized, and the inner face of which is platinized. The twoelectrodes press against each other by means of. a spring or by gravity,and one of them presses upon 7 -the inner or platinized face of thediaphragm.

Serial No. 4741190- (No model.)

The circuit is formed through the carbonized surface of the diaphragmaround to its platinized surface, where two paths are provided for it,one through the two electrodes, and another through the spring or sup- 55 port of and to the first electrode, and then to the second electrode.In the rear of this diaphragm is pivoted a thin iron diaphragm, near thesurface of which are located the poles of a horse shoe permanent magnet;this diaphragm is kept away from the platinized surface of the glassdiaphragm by means of a light spring. A magnetic circuit is formed fromthe poles of the magnet through the iron diaphragm; and as the poles areplaced very near'the iron diaphragm, which is also very near theplatinized surface of the glass diaphragm, the said surface also isaffected and becomes a part of the said magnetic circuit, the resultbeing that the said iron diaphragm acts as a damper upon the Vibrationsof the glass diaphragm, and at the same time modifies the currentflowing across the platinized surface. The effect of this arrangementis, that with the same amount of battery as is used in any ordinarytransmitter of the type referred to, speech can be transmitted to alonger distance.

I will now proceed to describe my inven-. tion in detail, and to pointout the same in the appended claims.

0f the drawingsFigure 1 is a rear view of the operating parts of atelephone transmitter embodying my invention. Fig. 2;.is a section online y y of Fig. 1, showing-the month piece of the instrument. Fig. 3 isa section on line as :c of Fig. 2, showing the mouth piece, and theinclosing box in dotted lines.

I have shown my invention as embodied in the Blake type of microphonictelephone transmitters, but it can be associated with all the forms oftransmitters that I am acquainted with.

1 indicates the front of the instrument pro- 9 5 vided with a mouthpiece and resonating chamber.

2 is the iron plate which supports the diaphragm and which is providedwith an arm a which supports the bar 11 which carries the electrodes 7and 9 by means of their metal springs 8 and 10; and the arm I) whichcarries the adjusting screw 12, all in a well known manner.

3 represents a diaphragm of glass, porcelain, or of any other insulatingmaterial which is capable of acting as avibrator; it has upon itsperiphery a rubber ring or cushion 6; the diaphragm is held to the ironframe 2 by means of metal clips 26, which press upon the rubber ring 6.The outer or front face 4 of the diaphragm is covered with carbon,applied in any suitable manner, as for instance, a mixture may beprepared of powdered carbon,with muriatic orsulphuric acid to which isadded shellac, which is then put on the surface of the glass by means ofa brush. The inner face of the diaphragm is platinized in any suitableway.

Fig. 2 shows the circuit connections when the transmitter is used withthe primaryt' of an inductive coil I; starting from the battery B, itextends by conductor 17 to one edge of the carbonized surface of thediaphragm, thence across its surface to the metal springs e and d to theinner or rear platinized face of the diaphragm, and across it to theplatinum electrode 7, or through a shunt path by wire 18 to the platinunelectrode 7 and carbon electrode 9, supporting springs 10, conductor 19,primary i of inductive coil I through the switch 3 (when the telephoneis removed from its hook) to the opposite pole of the battery B. Thiscircuit is opened by the switch 3 when the telephoneisupon thehookin theusualmanner. I find that beneficial results follow from the employmentof the diaphragm so constructed, the conducting surfaces of which form apart of the circuit. The carbonized and platinized surfaces 4 and 5assist the electrodes 7 and 9 in varying the battery current of thelocal circuit, for as the diaphragm vibrates under the force of airvibrations produced by the voice, the surfaces contract and expandrespectively and thus decrease and increase or vary the current, theelectrodes meanwhile simultaneously performing the same functions. Ifind that there is less liability of the electrodes separating orbreaking under loud sounds, and more battery can be placed in circuit,and a greater relative efiect produced by the usual amount of battery.13 is an extension of the arm a and has secured to it a depending lever14 to the lower end of which isfastenedapermanentmagnet16. Bymeans ofthe screw 15 the poles of the magnet may be adjusted closely to thesurface of a softiron diaphragm 22, shown as of semi-circular form, andhung by two arms 25, in bearings 24. The diaphragm 22 is hung very nearto the platinized face 5 of the diaphragm 3 and its lower edge isprevented from touching it by the fiat spring 23. By means of the magnet16 and the diaphragm 22, a constant magnetic circuit is establishedthrough the latter, and by the proximity of the iron diaphragm to theplatinized surface 5, the latter is at all times made a part of the saidmagnetic circuit, which serves as a damper to the undue vibrations ofthe diaphragm 3, and to some extent the said magnetic circuit affectsthe voltaic circuit flowing across the said platinized surface when itforms a part of the primary circuit, as described.

In Fig. 4 I have shown a substitute for the solid carbon electrode 9amass of powdered carbon m inclosed in a silk case, which is pressedagainst the platinum electrode 7 as is usual with the solid electrode.

Having thus explained the nature of the invention and described a way ofconstructing and using the same, though without attempting to set forthall of the forms in which it may be made or all the modes of its use, itis declared that what is claimed is- 1. In a microphonic telephonetransmitter, the combination of a diaphragm of glass, or otherinsulating material, the outer surface of which is carbonized and theinner surface of which is platinized; of two electrodes in contactsuspended by suitable conducting supports, one of said electrodes beingin contact with said platinized surface, all included in a batterycircuit, substantially as described.

2. In a microphonic telephone transmitter, the combination of adiaphragm of insulating material as glass, having its outer surfacecarbonized and its inner surface platinized, the two surfaces beingconnected to each other; of two electrodes in contact, suspended bysuitable conducting supports, one of the said electrodes being also incontact with said platinized surface, and also connected thereto throughits support, all included in a battery circuit, substantially asdescribed.

3. In a microphonic telephone transmitter, the combination of adiaphragm of insulating material as glass, the outer surface of which iscarbonized and the inner surface of which is platinized, the twosurfaces being connected; of two suitably supported electrodes incontact, one of said electrodes being also in contact with saidplatinized surface, all included in a battery circuit, as described; andan iron diaphragm hung as described near the platinized suface of saiddiaphragm, and a permanent magnet having its pole or poles near saidiron diaphragm, as and for the purpose described.

t. In a microphonic telephone transmitter, the combination of adiaphragm of insulating material as glass provided with a rubber ringand held in a suitable frame, the outer surface of which is carbonizedand the inner surface of which is platinized, the two surfaces beingconnected; of two electrodes in contact suspended by conducting supportsand provided with means of adjustment, one of the said electrodes beingalso in contact with said platinized surface, all included in a batterycircuit, as described.

5. In a microphonic telephone transmitter, the combination of adiaphragm of insulating material as glass, provided with a rubber ringand held in a suitable frame, the outer surface of which is carbonizedand the inner surface of which is platinized, the two surfaces beingconnected; of two electrodes in contact suspended by conducting supportsand provided with means of adjustment, one of the said electrodes beingalso in contact with said platinized surface, all included in a batterycircuit, as described; of an iron diaphragm hung as described-near theplatinized surface of said diaphragm, and a permanent magnet providedwith means of adjustment, having its poles near said iron diaphragm, asand for the purpose described.

In testimony whereof I have signed my I 5 name to this specification, inthe presence of two subscribing witnesses, this 6th day of May, A. D.1893.

HERBERT S. PAGE.

Witnesses:

ARTHUR W. CRossLEY, F. PARKER DAVIS.

